Non-circular vent pin for golf ball injection mold and golf ball formed therefrom

ABSTRACT

An improved vent pin for a golf ball injection mold is characterized by a non-circular configuration so that a non-circular dimple can be formed at one or both poles of the golf ball. The vent pin is coaxially arranged within a passage in the injection mold which is aligned with a radius of the ball which passes through one of the poles thereof. The pin is operable between a normal position where the end of the pin closes the passage lower end and a retracted position where the pin end is withdrawn into the passage so that air from a cavity of the mold where the cover layer of the ball is formed can be vented during delivery of thermoplastic material to the cavity to form the golf ball cover.

BACKGROUND OF THE INVENTION

[0001] In the golf ball manufacturing process, it is common practice toform the cover of the ball using injection molding. A mold comprising apair of parallel plates containing opposed hemispherical cavities isused to form a spherical cavity within which a golf ball core issuspended by retractable pins. Thermoplastic material is supplied to thecavity along a parting line defined where the hemispherical cavitiesterminated at the surface of the molding plates. The thermoplasticmaterial surrounds the core to form the cover layer of the ball. Ventpins in the bottom of the hemispherical cavities, i.e. at the poles ofthe golf ball, allow air to exit the cavity as thermoplastic material isapplied thereto. Following evacuation, the vent pins plug the ventopenings and form pole dimples on the ball.

BRIEF DESCRIPTION OF THE PRIOR ART

[0002] Injection molds for forming golf balls are well-known in thepatented prior art. The Lavallee et al U.S. Pat. No. 5,122,046, forexample, discloses a retractable pin golf ball injection mold whereinthe clearance at the parting line is reduced to prevent a flash linefrom being formed at the equator of the ball when the mold plates areseparated to eject a finished ball therefrom. The Lavallee et al U.S.Pat. No. 5,827,548 improves on the earlier Lavallee et al patent byproviding a retractable pin golf ball injection mold wherein a coolingcircuit is provided in the mold plates to decrease the setting time ofthe thermoplastic material and a two-stage ejector mechanism is providedto independently eject excess thermoplastic material from the runnersused to supply the material to the cavities and to eject the finishedgolf ball from the mold cavity.

[0003] Most golf ball injection molds of the prior art include a ventpin to allow air to be evacuated from the cavities as thermoplasticmaterial is being supplied thereto to allow even distribution of thethermoplastic material around the golf ball centers. Because the ventpins have a circular cross-sectional configuration, the pole dimples onthe ball are always circular. It has not been possible, therefore, withprior golf ball injection molds to form a dimpled golf ball withouthaving circular dimples at the poles. However, owing to the realizationof the influence of dimple configurations on ball flight, many golfballs today are formed with noncircular dimples. It is thus desirable tobe able to form a golf ball with an injection molded cover layer whereinall of the dimples, including those at the poles of the ball, have anon-circular configuration.

SUMMARY OF THE INVENTION

[0004] Accordingly, it is a primary object of the present invention toprovide a vent mechanism for a golf ball injection mold containing aspherical cavity in which a cover layer is applied to a golf ball coreto form a dimpled golf ball. The mold contains a vent passagecommunicating with the spherical cavity and a vent pin is arrangedwithin the passage. The passage extends from the cavity along a radiusof the golf ball through one of the poles thereof. The passage has anon-circular end communicating with the cavity, and the pin is operablebetween a normal position wherein an end of the pin closes the passagelower end and a retracted position wherein the pin end is arrangedwithin the passage and spaced from the cavity to allow air to enter thepassage from the cavity as thermoplastic material is supplied to thecavity to form the cover layer on the ball. The pin end has anoncircular cross-sectional configuration corresponding with that of thepassage end so that a dimple formed by the pin at the pole of the golfball has a non-circular configuration.

[0005] According to a further object of the invention, the pin is alsooperable between an extended position wherein the pin end is arrangedwithin the cavity to eject the golf ball therefrom.

[0006] Another object of the invention is form a golf ball having acover layer containing all non-circular dimples. The cover layerincludes two hemispherical surfaces formed by hemispherical cavities ofan injection mold. The hemispherical surfaces are identical and arejoined at the equator of the golf ball. Each hemispherical surfaceincludes a plurality of first non-circular dimples formed by projectionson the surfaces of the hemispherical cavities and a second non-circulardimpled formed at the pole of the golf ball, the pole dimple beingformed by a noncircular vent pin of the mold. Preferably, none of thedimples overlap. They may have the same or different configurations andsizes.

BRIEF DESCRIPTION OF THE FIGURES

[0007] Other objects and advantages of the invention will becomeapparent from a study of the following specification when viewed in thelight of the accompanying drawings, in which:

[0008]FIG. 1 is a sectional view of a golf ball injection mold apparatusincluding a non-circular vent pin according to the invention;

[0009] FIGS. 2A-2C are partial schematic views showing the displacementof the vent of the invention between retracted, normal, and extendedpositions, respectively;

[0010]FIG. 3 is a bottom view of the vent pin showing an oblongconfiguration of the pin end;

[0011]FIG. 4 is a bottom view of the vent pin showing an ellipticalconfiguration of the pin end; and

[0012]FIG. 5 is a plan view of a golf ball according to the inventionwith noncircular dimples on the ball surface, including at the poles ofthe ball.

DETAILED DESCRIPTION

[0013] As shown in FIG. 1, a golf ball injection mold according to theinvention includes upper 2 and lower 4 plates which can be displacerelative to one another in a conventional manner between the contiguousposition shown and a spaced position. The lower plate 4 includes atleast one hemispherical cavity 6 in the upper surface thereof, while theupper plate 2 includes a corresponding hemispherical cavity 8 in thelower surface thereof. A parting line is defined where eachhemispherical cavity terminates with the corresponding surface. When theplates are brought together in contiguous relation as shown, therespective upper and lower hemispherical cavities cooperate to define aspherical cavity for forming a golf ball.

[0014] Each hemispherical cavity includes a patterned surface 10 whichwill define a dimple pattern in the outer surface of the golf ball. Theupper hemispherical cavity 8 also includes a plurality of retractablecore pins 12 and the lower hemispherical cavity 6 includes a pluralityof retractable core pins 14. The pins have axes perpendicular to theparting line of the respective plates and are extensible into thespherical cavity to support a golf ball core during the injectionmolding process. Extension and retraction of the core pins isaccomplished through displacement of a conventional piston mechanism(not shown).

[0015] In order to supply thermoplastic material to the cavity, a runneris provided in the upper and lower plates. The runner 16 comprises anetwork of feeder lines in the surfaces of the upper and lower plateswhich define flow channels when the plates are in contiguous relation.The runner is connected with each cavity via gates 18 at the partingline. Accordingly, thermoplastic material is supplied to the cavity atvarious locations around the parting line for even distribution aboutthe core of the golf ball. Vent pins 20 are provided at the bottom ofthe upper and lower hemispherical cavities to evacuate air from thespherical cavity as thermoplastic material is supplied thereto. Ifdesired, a vacuum 22 may be connected with each vent pin 20 to assist indrawing air from the cavity so that the thermoplastic material may moreevenly be distributed around the ball core for even coverage thereof. Todecrease the time required for cooling and setting of the thermoplasticmaterial on the golf ball core, a coolant such as water is suppliedadjacent to each cavity via channels 24, 26 in the upper and lowerplates, respectively.

[0016] Each vent pin is arranged in a passage in the mold plates, thepassage and the axis of the pins being aligned with a radius of the golfball that passes through the poles of the ball. All of the vent pinshave a similar structure, so only one vent pin will be described ingreater detail in connection with FIGS. 2A-2C. The interior of thepassage 28 has two widths, W1 and W2. The greater width W1 is spacedfrom the spherical cavity 30 and the narrower width W2 is adjacent thespherical cavity. The pin also has two widths W3 and W4. The width W3 isremote from the free end of the pin and is less than the width W4 whichis at the end of the pin. The width W4 corresponds generally with thewidth W2 so that the pin end can pass through or close the end of thepassage.

[0017] More particularly, the pin is displaced relative to the passage28 by a displacement mechanism 32 between a retracted position shown inFIG. 2A where the pin is within the passage and the pin end is spacedfrom the spherical cavity, a normal position shown in FIG. 2B were thepin end closes the end of the passage, and an extended position shown inFIG. 2C where the pin end is arranged beyond the passage and in thespherical cavity. With the pin in the retracted position shown in FIG.2A, air from the cavity 30 is vented into the passage during delivery ofthermoplastic material to the cavity to form the golf ball cover layer.When the cavity has been filled, the displacement mechanism 32 moves thepin to its normal position shown in FIG. 2B to close the opening to thepassage. Following curing of the cover layer, the displacement mechanism32 moves the pin to the extended position to eject a golf ball from thecavity.

[0018] Preferably, when the pin is in the normal position of FIG. 2B,the pin end protrudes slightly into the spherical cavity to form adimple on the pole of the golf ball. The pin end bottom surface thus ispreferably convex. Unlike conventional vent pins, however, the pin ofthe present invention is non-circular, as is the opening to the passagefrom the spherical cavity. Accordingly, non-circular dimples are formedat the poles of the golf ball. Examples of non-circular pins are shownin FIGS. 3 and 4 wherein oblong and elliptical vent pins are shown,respectively. Of course, any desired non-circular shape may be providedfor the pin, including star, tear-drop, and geometrical configurationsto form correspondingly shaped dimples at the poles.

[0019] The resulting golf ball is shown in FIG. 5. The ball has twohemispherical surfaces 34, 36 formed by the hemispherical cavities 6, 8in the mold plates. The surfaces meet at the equator E of the ball wherethe parting line is formed. The pole dimples P formed by thenon-circular vent pins are also non-circular. In the example of FIG. 5,the pole dimple is elliptical. Non-circular dimples 38 are formed in theball surface by the patterns 10 in the hemispherical cavities. Ifdesired, all of the dimples on the ball surface may have the sameconfiguration and size. Alternatively, different sized dimples may beprovided. Moreover, a combination of differently configured dimples maybe provided on the ball surface. In FIG. 5, the dimples 38 a areelliptical and the dimples 38 b are oblong. The dimples can be arrangedin a repeatable pattern in each hemisphere, so long as both hemisphereshave the same pattern and configurations of dimples.

[0020] The golf ball according to the invention having all non-circulardimples, including the pole dimples, has different flightcharacteristics than traditional golf balls having circular dimples.These characteristics reduce hooking or slicing of the ball in flightand also increase the distance that a ball will carry.

[0021] While the preferred forms and embodiments of the invention havebeen illustrated and described, it will be apparent to those of ordinaryskill in the art that various changes and modifications may be madewithout deviating from the inventive concepts set forth above.

What is claimed is:
 1. A vent mechanism for a golf ball injection moldcontaining a spherical cavity in which a cover layer is applied to agolf ball core to form a dimpled golf ball, comprising a solid pincoaxially arranged within a passage in the injection mold, the passageextending from the cavity along a radius of the golf ball through one ofthe poles thereof and having a non-circular end communicating with thecavity, said pin being operable between a normal position wherein an endof said pin closes said passage lower end and a retracted positionwherein said pin end is arranged within said passage and spaced from thecavity to allow air to enter said passage from the injection moldcavity, said pin end having a non-circular cross-sectional configurationcorresponding with that of said passage end, whereby a dimple formed bysaid pin at the pole of the golf ball has a non-circular configuration.2. A vent mechanism for a golf ball injection mold as defined in claim1, wherein said pin end has a convex configuration.
 3. A vent mechanismfor a golf ball injection mold as defined in claim 2, wherein said pinis further operable between an extended position wherein said pin end isarranged within the cavity to eject a golf ball therefrom.
 4. A ventmechanism for a golf ball injection mold as defined in claim 3, andfurther comprising means for displacing said pin between said extended,normal and retracted positions.
 5. A vent mechanism for a golf ballinjection mold as defined in claim 4, wherein said pin end has an oblongcross-sectional configuration.
 6. A vent mechanism for a golf ballinjection mold as defined in claim 4, wherein said pin end has anelliptical cross-sectional configuration.
 7. An injection mold forapplying a cover layer to golf balls, comprising (a) upper and lowersupport plates each containing at least one hemispherical cavity, saidupper and lower hemispherical cavities being adapted to mate to defineat least one spherical cavity in which a core of a golf ball issupported when said plates are brought together; (b) means for supplyingthermoplastic material to said cavities to form a cover on the golf ballcore; and (c) means for venting air from said cavities as thermoplasticmaterial is supplied thereto, each of said venting means comprising apin arranged within a vent passage of said plates communicating withsaid spherical cavities, respectively, said pin having an axis extendingalong a radius of said cavity through a pole of the golf ball beingformed therein, said pin being operable between a normal positionwherein an end of said pin closes an end of said passage adjacent tosaid cavity and a retracted position wherein said pin end is arrangedwithin said passage and spaced from said cavity to allow air to entersaid passage from the cavity, said pin end having a noncircularcross-sectional configuration, whereby a dimple formed by said pin atthe pole of the golf ball has a non-circular configuration.
 8. Aninjection mold as defined in claim 7, wherein said pin end has a convexconfiguration.
 9. An injection mold as defined in claim 8, wherein saidpin is further operable between an extended position wherein said pinend is arranged in said cavity to eject a golf ball therefrom.
 10. Aninjection mold as defined in claim 9, and further comprising means fordisplacing said pin between said extended, normal and retractedpositions.
 11. An injection mold as defined in claim 10, wherein saidpin end has an oblong cross-sectional configuration.
 12. An injectionmold as defined in claim 10, wherein said pin end has an ellipticalcross-sectional configuration.
 13. A dimple pattern for a golf ballhaving a cover layer formed by an injection mold, the cover layercomprising two hemispherical surfaces formed by hemispherical cavitiesof the injection mold, said hemispherical surfaces being joined at anequator of the golf ball, each of said hemispherical surfaces beingidentical and including a plurality of first non-circular dimples formedby projections on surfaces of the hemispherical cavities and a secondnon-circular dimple formed at the pole of the golf ball, the pole dimplebeing formed by a non-circular vent pin of the mold.
 14. A dimplepattern for a golf ball as defined in claim 13, wherein none of saiddimples overlap.
 15. A dimple pattern as defined in claim 14, whereinsaid first and second dimples have the same configuration.
 16. A dimplepattern as defined in claim 15, wherein said first and second dimpleshave an elongated configuration.
 17. A dimple pattern as defined inclaim 15, wherein said first and second dimples have an ellipticalconfiguration.
 18. A dimple pattern as defined in claim 14, wherein thedimples of said first group of dimples have a different dimension.
 19. Adimple pattern as defined in claim 18, wherein the dimples of said firstgroup of dimples have at least two different configurations.